This invention relates to a bow string release and, more specifically, to a triggerless back-tension type release.
Various release devices are utilized in archery to assist the archer in pulling a bow string to a fully drawn position and then releasing the bow string to fire an arrow. Many of these devices include mechanical grippers that engage the bow string directly, or that engage nock elements mounted on the bow string. Other devices use rope looped about the bow string as the release mechanism with or without a mechanical trigger. In release devices of the latter kind, the looped rope is often subject to a twisting action as the archer draws the bow string due to a cocking or turning action of the archer""s wrist. This kind of twist or torque applied to the release rope can result in reduced arrow speed and accuracy.
Conventional triggerless back tension rope releases are disclosed in U.S. Pat. Nos. 5,694,915 and 5,965,884. In release aids of this type, it is simply a slight movement of the archer""s arm and/or hand, after the arrow is fully drawn, that causes the release of the rope loop from the rope loop hook on the sear, and the concurrent release of the bow string.
It is known to provide a sensitivity adjustment feature that permits adjustment of a xe2x80x9cpawlxe2x80x9d member that engages the sear to thereby change the degree of movement of the archer""s hand required to release the arrow. Increased sensitivity, however, increases the potential for accidental premature firing and/or the possibility of injury to the archer as is or her arm snaps back toward the face.
This invention relates to a triggerless back tension rope release that provides additional freedom of movement during draw by incorporating a two-link release head assembly, each link (a forward link and an intermediate link) freely pivotable about respective pivots relative to each other and to the release handle. The sear, formed with a rope loop hook, is pivotably mounted on the forward link while the pawl is adjustably fixed for movement with the intermediate link. This arrangement allows the archer to draw the bow, with the handle portion of the release assuming various positions and angles throughout the draw cycle, relative to the release head assembly but without affecting the relationship between the pawl and the sear. A locking mechanism is provided that includes mutually perpendicular drive and locking rods that can be actuated through a lever in the handle portion to lock the intermediate link of the release head in any desired position, but leaving the forward link that supports the sear free to swivel relative to its respective pivot axis, but with its arcuate range limited by the position of the intermediate link. In this locked position, the handle, intermediate link and pawl will move together relative to the sear. The arrow can then be released by the conventional movement or flexing of the hand and/or wrist that causes the pawl to move to a position that releases the sear for movement that concurrently causes the rope loop to disengage from the sear hook and the arrow to fire, under the influence of tension in the bow string.
The above described release head assembly and locking mechanism allows the archer to find the optimum draw position before locking the intermediate link, eliminating or at least significantly reducing any potential premature firing of the arrow.
It is another feature of the invention to fix the rope loop ends at a location on the forward link of the release head assembly that is closely adjacent and forward of the pivot pin of the sear, and more particularly, closely adjacent the rope loop hook on the sear. This arrangement insures that the release rope travels from its connection holes in the forward link in a straight line around the bow string and back to the sear hook, where the distance between the release rope lengths at the bow string is equal to or greater than the distance between the release rope lengths at the rope connection holes in the sear and the rope loop hook on the sear. In other words, the distance between the rope release lengths at the sear is substantially equal to or less than the diameter of the bow string. This insures that the bow string is maintained accurately in the exact same position of the release rope xe2x80x9ccradle,xe2x80x9d not allowing the bow string to slide or move to a varying positions, thereby maintaining a consistent amount of back tension travel to release the shot.
In another embodiment of the invention, the release head assembly is mounted in a fork that is freely rotatably adjustable through 360xc2x0 about a post projecting from the release handle. The release head assembly may be locked in the desired position via the handle by means of a wedge-like locking pin.
Thus, in accordance with one aspect of the invention, there is provided a triggerless back tension release for use with a bow string, the release comprising a handle portion including at least two finger grooves with a post extending substantially perpendicularly away from the handle portion; a two-link release head assembly secured to a fork rotatably secured in the post for rotation about a longitudinal axis of the post, the two-link release head assembly including an intermediate link pivotably mounted on the fork and a forward link pivotably mounted to the intermediate link; a rope loop having two free ends secured to the forward link; and a sear pivotably secured to the forward link, the sear having a hook adapted to receive the rope loop.